There have been few attempts to use in vivo microscopy to examine the gingival microcirculation, despite the clinical evidence that many problems such as gingivitis, acute necrotizing ulcerative gingivitis, flap surgery procedures and peridontal disease, do or may arise from alterations in the gingival vasculature. One reason for this is the difficulty in using transmitted light microscopy in a basically opaque and difficult to reach tissue. In the past, this has necessitated the use of surgery. The primary goal of this proposal is the development of a non-invasive preparation for the in situ observations of the gingival microcirculation in the Golden Hamster. We will use a closed circuit television system with fluorescent microscopy to allow quantitation of changes in gingival microcirculation without surgical intervention. A bath or reservoir will be formed around a portion of the gingiva of the incisors. Physiological salt solution will be placed in the bath to maintain a moist and viable preparation and to allow for alteration of the local tissue environment (e.g. changes in pH, PCO2, calcium ion concentration, temperature and molar concentrations of drugs). Vascular diameters of the major vessel subtypes will be measured and protein leakage from the vasculature to the interstitial tissue will be quantitated. To test the preparation we will add molar concentrations of drugs to the bath to locally produce vasoconstriction, vasodilation and/or alter protein permeability in the gingival microcirculation. The use of local drug applications will allow us to examine the reactivity of gingival microcirculation without producing systemic effects that could lead to central reflexes. Situations which enhance sympathetic activity like direct nerve stimulation, high stress levels, or nicotine are associated with peridontal disease. Thus, our initial studies will determine the effects of catecholamines and nicotine on the gingival microcirculation. since an inflammatory process also accompanies gingivitis and may be a contributing factor in peridontal disease, we also plan to study the reactivity to agents which can cause edema such as bradykinin and histamine. This will be a non-invasive preparation and should allow us in future studies to determine the effects of aging in animal models of peridontal lesions as well as in humans.